This book shows how the change of water paradigm has become urgent, and provides evidence for new policies that expand water balance to green and virtual water. The issue of water security concerns drinking water supply but also food safety, linked to agricultural policy. Both rain-fed and irrigated agriculture play complementary roles in food security, and the water issue implies a holistic view of water resources. This view constitutes the book's backstory. The reader will find original ideas that can be applied everywhere because the example of Tunisia is typically a basis to illustrate a universally prevalent situation. The book deals with other important issues: desalination, wastewater recycling, water quality, groundwater overdraft, water savings, governance, knowledge valuing, education, information: upgrading the whole water systems for the future implies emancipation of the whole society.

Jamel Chahedis a hydraulics engineer and Doctor es sciences, Professor at the National Engineering School of Tunis, University of Tunis El Manar.His work focuses on transfers in industrial and environmental fluid systems, atmospheric dispersion, water governance and water management. His research has appeared as articles, books, book chapters, conference acts in specialized literature such as hydrology, water resources management, hydraulics, turbulence and transfers, environmental engineering. He actively contributed to the development of long-term vision for water security with a thematic focus on holistic water balance assessment. He has been involved in number of national and international academic research and technical programs. As visiting professor, associate researcher or guest speaker he joined number of international research teams at academic institutes, research laboratories and R&D centres.

Abdelkader Hamdaneis graduated from Institut National Agronomique de Paris (1971), and Ecole Nationale du Génie Rural, des Eaux et Forêts de Paris (1973). He is general engineer, formerly General Directorof the Medjerda Valley Development Company, General Director of Rural Engineering and Water Management Department of the Ministry of Agriculture and Water Resources of Tunisia. He has been member of several public companies boards operating in the field of water, and led several assessment missions in scientific and technical research institutions. He was a short-term professor of irrigation and drainage at the National Agronomic Institute of Tunis and the National Engineering School of Tunis. He is currently a Scientific Advisor at the National Agronomic Institute of Tunis, University of Carthage, involved in many national and international research programs, and consultant on water management in international organizations.

The World Water Issues.- Fifty years of water policies, 1960-2010.- The National Water Balance.- The holistic water balance:  Blue Water, Green Water and Virtual Water.- Managing water demand and unconventional resources.- Water Security in Tunisia: debated issues.- Conclusion.- References.